Doing fullbody workouts in a gym, dependent on which equipment is available, how many people I have to work in with, etc. can easily take 90 min, sometimes 2 hrs if its busy.

Saving abs for the end of each workout, I don't feel like I can put my all into it and/or I don't want to because I'm beat.

Would doing abs throughout the day, 3-4 days a week be a bad idea?
I have plates and a bench at home so I have a variety of things I could do for them. If I kept the volume the same, is this a feasible option?